CN113252572B - Optical fiber tip type photoacoustic gas sensing system and method - Google Patents
Optical fiber tip type photoacoustic gas sensing system and method Download PDFInfo
- Publication number
- CN113252572B CN113252572B CN202110504475.4A CN202110504475A CN113252572B CN 113252572 B CN113252572 B CN 113252572B CN 202110504475 A CN202110504475 A CN 202110504475A CN 113252572 B CN113252572 B CN 113252572B
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- cantilever beam
- photoacoustic
- gas
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
- G01N2021/1704—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids in gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N2021/4173—Phase distribution
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
- G01N2021/451—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods for determining the optical absorption
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
- G01N2021/458—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods using interferential sensor, e.g. sensor fibre, possibly on optical waveguide
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention provides an optical fiber tip type photoacoustic gas sensing system and method, and belongs to the technical field of optical trace gas detection. The gas sensing system comprises a narrow-linewidth laser light source, a wide-spectrum detection light source, a wavelength division multiplexer, an optical circulator, a spectrometer, a computer, a single-mode optical fiber and an optical fiber tip type photoacoustic sensing probe. Narrow-linewidth laser and wide-spectrum detection light are coupled by a wavelength division multiplexer and are simultaneously transmitted to the optical fiber tip type photoacoustic sensing probe through a single optical fiber, and a common air cavity is adopted to be simultaneously used as a photoacoustic gas absorption cell and a Fabry-Perot interference cavity; the gas to be detected freely diffuses into the micro air chamber through the cantilever beam gap, and the photoacoustic signal generated is detected by the cantilever beam diaphragm sensitive to sound waves. The scheme of the invention has the advantages of small probe volume, high response speed, simple structure, intrinsically safe property, high sensitivity and the like, and provides a very competitive technical scheme for detecting trace gas in a narrow pipeline by using the optical fiber photoacoustic gas sensing technology.
Description
Technical Field
The invention belongs to the technical field of optical trace gas detection, and relates to an optical fiber tip type photoacoustic gas sensing system and method.
Background
Methane is a colorless and odorless combustible gas and is an important clean energy source, but the methane gas can also cause disastrous accidents such as explosion and the like. However, some monitoring scenarios (such as narrow pipelines and the like) put high demands on the size of the sensor, and therefore, it is of great significance to design a miniature gas sensor with high sensitivity.
Common trace methane gas detection methods include gas chromatography, electrochemical sensing, photoacoustic spectrometry, Raman spectrometry and the like, wherein the photoacoustic spectrometry (PAS) method has the advantages of high sensitivity and maintenance-free property. However, the existing photoacoustic spectroscopy gas detection system has the problems of large volume, complex system and the like. In order to further reduce the volume of the photoacoustic probe while ensuring the detection sensitivity, the document Fiber-optical photoacoustic sensor for remote monitoring of the gas micro-leak [ J ] Optics Express,2019.27(4):4648-4 and the document Parylene-C diaphragm-based low-frequency photoacoustic sensor for space-limited gas detection [ J ] Optics and laser in Engineering,2020.134:106288 reported a trace gas detection system based on photoacoustic spectroscopy in which a Fiber-optic Fabry-Perot acoustic sensor and a small photoacoustic cell were combined to make the volume of the micro gas cell in the Fiber-optic tip photoacoustic sensing probe less than 74 μ L. However, because a high-sensitivity optical fiber acoustic wave sensor is used, two optical fibers are often connected to the probe, one optical fiber transmits excitation light for exciting a photoacoustic signal, and the other optical fiber transmits probe light for forming a fabry-perot interferometer, which occupies redundant space and is not easy to further reduce the volume of the probe. The document Miniature fiber-tip photoacoustic spectrometer for trace gas detection [ J ]. Optics Letters,2013.38(4):434 proposes a single fiber photoacoustic spectroscopy gas detection system that can reduce the volume of the photoacoustic probe. However, the use of active devices such as gas valves limits the miniaturization of such sensors. In addition, the intensity demodulation method used needs to use a narrow-band fiber tunable filter to filter out the probe light, and the center wavelength of the tunable filter is easily affected by temperature and drifts, so that the scheme is not favorable for field application. Therefore, the design of the optical fiber tip type photoacoustic gas sensing system which is small in size, high in sensitivity and intrinsically safe has important application value.
Disclosure of Invention
The invention aims to provide an optical fiber tip type photoacoustic gas sensing system and method. The problems of large volume, complex system, poor anti-electromagnetic interference capability and the like of a methane gas sensor generally existing can be effectively solved, and the application of the optical fiber photoacoustic sensing technology in scenes with electromagnetic interference environments or narrow pipelines and the like is further expanded.
The principle of the invention is as follows:
the narrow linewidth laser with the center wavelength adjusted at the methane absorption peak and the broad spectrum detection light source are coupled into the wavelength division multiplexer and transmitted in the same optical fiber. The narrow line width laser excites gas molecules in the terminal photoacoustic probe cavity to generate photoacoustic signals, and a cantilever beam diaphragm on the end face of the photoacoustic probe is pushed to vibrate. An air gap between the end face of the optical fiber and the cantilever beam forms a Fabry-Perot interference cavity, and acoustic wave information is obtained by adopting spectrometer demodulation, so that the second harmonic amplitude of the photoacoustic signal is measured, and further the concentration information of the gas is obtained.
The first-order resonance frequency of the rectangular cantilever beam etched on the end face of the photoacoustic probe can be expressed as follows:
where E is the Young's modulus of the cantilever beam material, ρ is the material density, and L and t are the length and thickness of the cantilever beam, respectively. For example, a silicon-based cantilever beam is adopted, and E is 169Gpa and rho is 2.33g/cm3(ii) a If the length of the cantilever beam is 0.5mm and the thickness is 2 μm, the first-order resonance frequency is calculated to be about 11,000 Hz.
The demodulation resolution of the fiber fabry-perot cavity length is determined by the contrast of the interference spectrum. The coupling efficiency of the reflected light field and the fundamental mode light field is as follows:
wherein d is the cavity length, r0Is the radius of the mode field of the fiber,
is the reflected light field mode field radius. The contrast can be expressed as:
wherein, IMAXAnd IMINRespectively the maximum and minimum of the intensity, R1And R2Respectively the reflectivity of the fiber end face and the cantilever beam.
In order to ensure the demodulation stability, the sampling point number of each period of the spectrum is set to be 4, and the spectrum range xipN/4-1. The maximum demodulation cavity length of the demodulation system can be expressed as:
wherein λ iscAnd Δ λ are the central wavelength and spectral range of the light source, respectively. For lambdacA white light interference spectrometer with 1550nm, 70nm Δ λ and 512pixels, calculated to have a maximum demodulation cavity length of 2.2 mm.
The photoacoustic signal amplitude can be expressed as:
where α is the absorption coefficient of the target gas, γ is the gas heat capacity ratio, P0Is the optical power of the photoacoustic excitation light source, V is the cavity volume, and f is the frequency. Tau is1And τ2Respectively, the thermal damping time and the time constant of the damping effect due to the gas and thermal energy flow. At a frequency of 11,000Hz, PPA(f) The maximum value is reached at a radius of-0.18 mm. The amplitude-frequency response of a photoacoustic system can be expressed as:
A(f)＝PPA(f)AcRc(f)， (6)
wherein A iscIs the area of the cantilever beam, Rc(f) Is the amplitude-frequency response of the cantilever beam.
According to the equations (2), (3), (5) and (6), the interference contrast/photoacoustic system response amplitude-cavity length function curve is obtained, as shown in fig. 3. It can be seen that when the cavity length is greater than 0.2mm, the interference contrast decreases as the photoacoustic signal amplitude increases. In order to realize high sensitivity of the detection system and ensure stable operation of the demodulation system, the length of the photoacoustic cell is selected to be 2.2 mm; to reduce the sensor diameter, the inner radius of the air cavity is designed to be 0.18 mm. Thus, the air cavity volume is only 0.22 μ L.
The technical scheme of the invention is as follows:
an optical fiber tip type photoacoustic gas sensing system comprises a narrow line width laser light source 1, a wide spectrum detection light source 2, a wavelength division multiplexer 3, an optical circulator 4, a spectrometer 5, a computer 6, a single-mode optical fiber 7 and an optical fiber tip type photoacoustic sensing probe 8; the narrow linewidth laser light source 1 is connected to the reflection end of the wavelength division multiplexer 3, and the common end of the wavelength division multiplexer 3 is connected to the optical fiber tip type photoacoustic sensing probe 8 through the single mode optical fiber 7; laser output by the narrow linewidth laser light source 1 is incident to the optical fiber tip type photoacoustic sensing probe 8 through the wavelength division multiplexer 3 and the single-mode optical fiber 7; the optical circulator 4 is connected to the transmission end of the wavelength division multiplexer 3, wide spectrum light emitted by the wide spectrum detection light source 2 enters the single mode optical fiber 7 through the optical circulator 4 and the wavelength division multiplexer 3 at the same time, interference occurs in the optical fiber tip type photoacoustic sensing probe 8, returned interference signals are transmitted to the spectrometer 5 through the wavelength division multiplexer 3 and the optical circulator 4, and interference spectra are transmitted to the computer 6 for processing and displaying.
The wavelength of the narrow-line-width laser light source 1 is 1650.9nm or 1653.7nm, and the line width is less than 1 pm.
The wide spectrum detection light source 2 is a near infrared broadband light source, the central wavelength is 1550nm, and the spectrum width is not less than 20 nm.
The wavelength division multiplexer 3 has a transmission end with a working wavelength range of 1520-.
The wavelength range of the spectrometer 5 is 1525-1565nm, and the frame rate is higher than 10 kHz.
The length range of the single-mode optical fiber 7 is 1m-10 km.
The optical fiber tip type photoacoustic sensing probe 8 comprises an optical fiber ceramic contact pin 9, a micro air chamber 10, an optical fiber end face 11 and a sound wave sensitive cantilever diaphragm 12. The acoustic wave sensitive cantilever beam diaphragm 12 is arranged on the right side of the micro air chamber 10, and the gas to be detected is diffused into the air chamber 10 through a cantilever beam gap on the acoustic wave sensitive cantilever beam diaphragm 12; the surface of the acoustic wave sensitive cantilever beam diaphragm 12 is plated with gold, and the length, the width and the thickness of the acoustic wave sensitive cantilever beam diaphragm are respectively 0.5mm, 0.3mm and 2 mu m; the acoustic wave sensitive cantilever beam diaphragm 12 and the optical fiber end face 11 form a Fabry-Perot cavity, and the cavity length is 2.2 mm.
A method for sensing photoacoustic gas by using a fiber tip comprises coupling narrow-linewidth laser and wide-spectrum detection light by a wavelength division multiplexer, transmitting the coupling light and the wide-spectrum detection light to a fiber tip photoacoustic sensing probe by a single fiber, and simultaneously using a common air cavity as a photoacoustic gas absorption cell and a Fabry-Perot interference cavity; the gas to be detected freely diffuses into the micro air chamber through the cantilever beam gap, and the photoacoustic signal generated is detected by the cantilever beam diaphragm sensitive to sound waves. The method comprises the following specific steps:
firstly, a narrow linewidth laser light source 1 outputs laser with a specific wavelength, the laser is transmitted in a single-mode optical fiber 7 through a reflection end of a wavelength division multiplexer 3, and enters an optical fiber tip type photoacoustic sensing probe 8 through an optical fiber end face 11 at the right end of an optical fiber ceramic contact pin 9; the gas to be measured enters the micro air chamber 10 through a cantilever beam gap etched on the acoustic wave sensitive cantilever beam diaphragm 12; the incident laser excites the gas to be measured in the micro gas chamber 10 to generate a photoacoustic effect, and causes periodic thermal expansion of the gas to generate an acoustic signal, so that the acoustic wave sensitive cantilever beam diaphragm 12 is forced to vibrate.
Then, a Fabry-Perot interference cavity is formed by the optical fiber end face 11 and the acoustic wave sensitive cantilever beam diaphragm 12; the wide spectrum light emitted by the wide spectrum detection light source 2 passes through the optical circulator 4, the wavelength division multiplexer 3 and the single mode fiber 7 in sequence, then enters the micro air chamber 10 through the fiber end face 11 at the right end of the fiber ceramic contact pin 9, and irradiates the sound wave sensitive cantilever beam diaphragm 12. The probe light is reflected by the end of the etched cantilever beam on the acoustic wave sensitive cantilever beam membrane 12 and forms Fabry-Perot interference in the cavity.
Finally, the forced vibration generated by the acoustic wave sensitive cantilever beam diaphragm 12 can cause the cavity length of the Fabry-Perot cavity to periodically change, so that the phase of the interference spectrum changes, the spectrometer 5 receives the interference spectrum and transmits information to the computer 6 for processing, the dynamic cavity length information of the Fabry-Perot cavity is demodulated, and the concentration of the gas is calculated according to the amplitude of the extracted second harmonic signal.
The invention has the beneficial effects that: the narrow linewidth excitation light and the wide-spectrum detection light are coupled into one optical fiber by using a wavelength division multiplexer for transmission, so that the system structure is simplified, and the problem of interference of the reflected narrow linewidth excitation light on a Fabry-Perot interference spectrum is solved; a common air cavity is adopted as a photoacoustic cell and a Fabry-Perot interference cavity at the same time, and the common air cavity is combined with an MEMS (micro-electromechanical system) technology to be designed into a needle point type sensing probe, wherein the diameter of the probe is only about 1 mm; the volume of the ultra-small air chamber smaller than 1 mu L can also greatly improve the response speed of the air. The scheme of the invention has the advantages of small probe volume, high response speed, simple structure, intrinsically safe property, high sensitivity and the like, and provides a very competitive technical scheme for detecting trace gas in a narrow pipeline by using the optical fiber photoacoustic gas sensing technology.
Drawings
FIG. 1 is a schematic diagram of the system architecture of the present invention.
FIG. 2 is a schematic diagram of a fiber optic tip photoacoustic gas sensor.
Figure 3 is a plot of interference contrast, photoacoustic system response amplitude versus cavity length.
In the figure: 1 narrow linewidth laser light source; 2 wide spectrum detection light source; 3 a wavelength division multiplexer; 4, an optical circulator; 5, a spectrometer; 6, a computer; 7 a single mode optical fiber; 8, a fiber tip type photoacoustic sensing probe; 9 optical fiber ceramic contact pin; 10 micro air chamber; 11 an optical fiber end face; 12 an acoustic wave sensitive cantilever membrane.
Detailed Description
The following detailed description of the invention refers to the accompanying drawings.
An optical fiber tip type photoacoustic gas sensing system mainly comprises a narrow line width laser light source 1, a wide spectrum detection light source 2, a wavelength division multiplexer 3, an optical circulator 4, a spectrometer 5, a computer 6, a single-mode optical fiber 7 and an optical fiber tip type photoacoustic sensing probe 8. Laser emitted by the narrow linewidth laser light source 1 is transmitted in a single-mode optical fiber 7 through the wavelength division multiplexer 3, enters the optical fiber tip type photoacoustic sensing probe 8 and excites gas to generate a photoacoustic effect; the wide spectrum light emitted by the wide spectrum detection light source 2 sequentially passes through the optical circulator 4, the wavelength division multiplexer 3 and the single mode fiber 7, enters the fiber tip type photoacoustic sensing probe 8, then is reflected to carry interference information, passes through the single mode fiber 7, the wavelength division multiplexer 3 and the optical circulator 4, is transmitted to the spectrometer 5 for signal processing, and finally is transmitted to the computer 6 for processing and displaying.
The narrow-linewidth laser light source 1 is a Distributed Feedback (DFB) laser with a central wavelength of 1650.9nm and a power of 10 mW. The wide spectrum detection light source 2 is an SLED light source with the center wavelength of 1550nm and the bandwidth of 50 nm. The wavelength division multiplexer 3 has a transmission end with a working wavelength range of 1520-. Spectrometer 5 is a high-speed micro spectrometer with a spectral acquisition rate of 5 kHz. The single mode fiber 7 is a G652 single mode fiber.
The optical fiber tip type photoacoustic sensing probe 8 comprises an optical fiber ceramic contact pin 9, a micro air chamber 10, an optical fiber end face 11 and a sound wave sensitive cantilever diaphragm 12. The length of the air cavity of the cylindrical micro air chamber 10 is 2.2mm, the diameter is 1.0mm, and the acoustic wave sensitive cantilever beam diaphragm 12 is arranged at the right end of the air chamber. The silicon-based cantilever beam etched on the acoustic wave sensitive cantilever beam diaphragm 12 is 0.5mm long, 0.3mm wide and 2 μm thick; the width of the gap of the etched rectangular cantilever beam is about 10 μm, so that the gas to be measured is diffused into the micro gas chamber 10. Incident light enters the micro air chamber 10 through the optical fiber end face 11 at the right end of the optical fiber ceramic contact pin 9, the gas to be detected is excited to generate a photoacoustic effect, and then the rectangular cantilever beam is forced to vibrate, so that the length of the Fabry-Perot interference cavity is changed. The detection light is incident into the micro air chamber 10 through the optical fiber end face 11 at the right end of the optical fiber ceramic ferrule 9, and the light carrying the interference information is coupled back into the optical fiber ceramic ferrule 9 again.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. An optical fiber tip type photoacoustic gas sensing system is characterized by comprising a narrow line width laser light source (1), a wide spectrum detection light source (2), a wavelength division multiplexer (3), an optical circulator (4), a spectrometer (5), a computer (6), a single-mode optical fiber (7) and an optical fiber tip type photoacoustic sensing probe (8); the narrow-linewidth laser light source (1) is connected to the reflection end of the wavelength division multiplexer (3), and the common end of the wavelength division multiplexer (3) is connected to the optical fiber sharp type photoacoustic sensing probe (8) through a single-mode optical fiber (7); laser output by the narrow-linewidth laser light source (1) is incident to the optical fiber tip type photoacoustic sensing probe (8) through the wavelength division multiplexer (3) and the single-mode optical fiber (7); the optical circulator (4) is connected to the transmission end of the wavelength division multiplexer (3), wide spectrum light emitted by the wide spectrum detection light source (2) enters the single mode fiber (7) through the optical circulator (4) and the wavelength division multiplexer (3), the wide spectrum light interferes with reflected detection light in the fiber tip type photoacoustic sensing probe (8), returned interference signals are transmitted to the spectrometer (5) through the wavelength division multiplexer (3) and the optical circulator (4), and the interference spectrum is transmitted to the computer (6) for processing and displaying;
the optical fiber tip type photoacoustic sensing probe (8) comprises an optical fiber ceramic contact pin (9), a micro air chamber (10), an optical fiber end face (11) and an acoustic wave sensitive cantilever diaphragm (12); the acoustic wave sensitive cantilever beam diaphragm (12) is arranged on the right side of the micro air chamber (10), and gas to be detected is diffused into the micro air chamber (10) through a cantilever beam gap on the acoustic wave sensitive cantilever beam diaphragm (12); the surface of the acoustic wave sensitive cantilever beam diaphragm (12) is plated with gold, and the length, the width and the thickness of the acoustic wave sensitive cantilever beam diaphragm are respectively 0.5mm, 0.3mm and 2mm
(ii) a The acoustic wave sensitive cantilever beam diaphragm (12) and the optical fiber end face (11) form a Fabry-Perot cavity, the cavity length is 2.2mm, and the inner radius of the Fabry-Perot cavity is designed to be 0.18
The volume of the Fabry-Perot cavity is 0.22
。
2. The optical fiber tipped photoacoustic gas sensing system of claim 1, wherein the narrow linewidth laser light source (1) has a wavelength of 1650.9nm or 1653.7nm and a linewidth of less than 1 pm.
3. The optical fiber tip type photoacoustic gas sensing system of claim 2, wherein the wavelength division multiplexer (3) has a transmission end with an operating wavelength range of 1520-1570nm and a reflection end with an operating wavelength range of 1600-1700 nm.
4. According to claim 1, 2 orThe optical fiber tip type photoacoustic gas sensing system is characterized in that the wide spectrum detection light source (2) is a near-infrared broadband light source, the central wavelength is 1550nm, and the spectrum width is not less than 20
。
5. The optical fiber tip type photoacoustic gas sensing system of claim 4, wherein the wavelength range of the spectrometer (5) is 1525 and 1565nm, and the frame rate is higher than 10 kHz.
6. A fiber-tipped photoacoustic gas sensing system according to claim 1, 2, 3 or 5, characterized in that the length of the single-mode fiber (7) ranges from 1m to 10 km.
7. An optical fiber tip type photoacoustic gas sensing method using the optical fiber tip type photoacoustic gas sensing system of any one of claims 1 to 5, characterized by comprising the following steps:
firstly, a narrow linewidth laser light source (1) outputs laser with specific wavelength, the laser is transmitted in a single-mode optical fiber (7) through a reflection end of a wavelength division multiplexer (3), and enters a Fabry-Perot cavity through an optical fiber end face (11) at the right end of an optical fiber ceramic contact pin (9); the gas to be measured enters the micro air chamber (10) through a cantilever beam gap etched on the acoustic wave sensitive cantilever beam diaphragm (12); the incident laser excites the gas to be detected in the micro gas chamber (10) to generate a photoacoustic effect, and causes periodic thermal expansion of the gas to generate an acoustic signal, so that the acoustic wave sensitive cantilever beam diaphragm (12) generates forced vibration;
then, a Fabry-Perot interference cavity is formed by the optical fiber end face (11) and the acoustic wave sensitive cantilever beam diaphragm (12); the wide spectrum light emitted by the wide spectrum detection light source (2) passes through the optical circulator (4), the wavelength division multiplexer (3) and the single-mode fiber (7) in sequence, then enters the Fabry-Perot cavity through the fiber end face (11) at the right end of the fiber ceramic contact pin (9), and irradiates the acoustic wave sensitive cantilever beam diaphragm (12); the tail end of a cantilever beam etched on the acoustic wave sensitive cantilever beam membrane (12) reflects the detection light and forms Fabry-Perot interference in the cavity;
and finally, the cavity length of the Fabry-Perot cavity is periodically changed by forced vibration generated by the sound wave sensitive cantilever beam diaphragm (12), so that the phase of the interference spectrum is changed, the interference spectrum is received by the spectrometer (5) and information is transmitted to the computer (6) for processing, the dynamic cavity length information of the Fabry-Perot cavity is demodulated, and the concentration of the gas is calculated according to the amplitude of the extracted second harmonic signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110504475.4A CN113252572B (en) | 2021-05-10 | 2021-05-10 | Optical fiber tip type photoacoustic gas sensing system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110504475.4A CN113252572B (en) | 2021-05-10 | 2021-05-10 | Optical fiber tip type photoacoustic gas sensing system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113252572A CN113252572A (en) | 2021-08-13 |
| CN113252572B true CN113252572B (en) | 2022-05-13 |
Family
ID=77222396
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110504475.4A Active CN113252572B (en) | 2021-05-10 | 2021-05-10 | Optical fiber tip type photoacoustic gas sensing system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113252572B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113567818B (en) * | 2021-08-16 | 2024-05-03 | 重庆大学 | Fabry-Perot partial discharge sensing device and method based on cantilever supporting structure |
| CN114088631B (en) * | 2021-11-18 | 2024-09-17 | 国网安徽省电力有限公司电力科学研究院 | Distributed online monitoring system and method for sulfur hexafluoride decomposition products |
| CN114062274A (en) * | 2021-11-18 | 2022-02-18 | 国网安徽省电力有限公司电力科学研究院 | Optical fiber photoacoustic sensing system and method for detecting dissolved gas in oil |
| CN114062273B (en) * | 2021-11-18 | 2024-06-11 | 国网安徽省电力有限公司电力科学研究院 | Anti-interference optical fiber photoacoustic gas sensing system and method |
| CN114076737B (en) * | 2021-11-18 | 2024-03-12 | 国网安徽省电力有限公司电力科学研究院 | Distributed online monitoring system and method based on optical fiber photoacoustic sensing |
| CN114324182B (en) * | 2021-12-24 | 2024-07-23 | 中国科学院电工研究所 | High-pressure SF6Decomposed gas detection device |
| CN116419137B (en) * | 2023-04-14 | 2024-06-04 | 郑州大学 | Optical microphone and microphone system based on hollow micro-cantilever |
| CN117233112A (en) * | 2023-09-04 | 2023-12-15 | 国网甘肃省电力公司电力科学研究院 | Micro optical fiber trace acetylene gas detection system and method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101936878B (en) * | 2010-07-28 | 2011-11-30 | 山东大学 | Photo-acoustic spectrum gas detecting system based on distributed feedback optical fiber laser |
| CN103439268B (en) * | 2013-09-05 | 2016-05-04 | 安徽大学 | High-sensitivity diaphragm type photoacoustic spectrum sensor based on self-mixing |
| CN111007015A (en) * | 2019-12-02 | 2020-04-14 | 暨南大学 | Optical fiber micro-air cavity photoacoustic cell, preparation method and dissolved gas detection method |
-
2021
- 2021-05-10 CN CN202110504475.4A patent/CN113252572B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113252572A (en) | 2021-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113252572B (en) | Optical fiber tip type photoacoustic gas sensing system and method | |
| WO2022121457A1 (en) | Optical fiber photoacoustic sensing probe and sensing system resistant to ambient noise interference | |
| JP5600850B2 (en) | Self-reference optical fiber sensor by stimulated Brillouin scattering | |
| CN101055243B (en) | Optical fiber gas sensing method and sensor | |
| Fu et al. | Small-volume highly-sensitive all-optical gas sensor using non-resonant photoacoustic spectroscopy with dual silicon cantilever optical microphones | |
| CN108051400B (en) | Scanning laser interference type optical fiber sound wave phase-locked detection system and method | |
| US20110019179A1 (en) | Self-Referenced Optical Fiber Sensor and Related Sensor Network | |
| CN103471701B (en) | A kind of fiber optic acoustic sensors and optical fiber acoustic sounding method | |
| CN112161931B (en) | High-sensitivity optical fiber photoacoustic gas detection system and method | |
| Wang et al. | Optical fiber acoustic sensor based on nonstandard fused coupler and aluminum foil | |
| CN101135577A (en) | Automatic tuning F-P optical fiber sensor | |
| Li et al. | Low-cost fiber optic extrinsic Fabry–Perot interferometer based on a polyethylene diaphragm for vibration detection | |
| Liu et al. | A compact fiber optic Fabry–Perot sensor for simultaneous measurement of acoustic and temperature | |
| CN112033908B (en) | Single-light-source optical fiber photoacoustic gas sensing system and method | |
| CN201034929Y (en) | Optical fiber gas sensors | |
| Li et al. | Differential Cantilever Enhanced Fiber-Optic Photoacoustic Sensor for Diffusion Gas Detection | |
| Wu et al. | Single fiber-type double cavity enhanced photoacoustic spectroscopy sensor for trace methane sensing | |
| Fan et al. | Compact optical fiber photoacoustic gas sensor with integrated multi-pass cell | |
| Huang et al. | VCSEL-based tilted fiber grating vibration sensing system | |
| Fu et al. | All-optical non-resonant photoacoustic spectroscopy for multicomponent gas detection based on aseismic photoacoustic cell | |
| CN114062273B (en) | Anti-interference optical fiber photoacoustic gas sensing system and method | |
| Zhu et al. | An acoustic sensor based on balloon-shaped microfiber Mach-Zehnder interferometer | |
| CN201083500Y (en) | Automatic tuning F-P optical fiber sensor | |
| Chyad et al. | Acoustic fiber sensors by Fabry-Perot interferometer technology | |
| Wang et al. | Cantilever-enhanced dual-comb photoacoustic spectroscopy |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |